Apple scab primary ascospore development is moving along in Vermont orchards, with most orchards having approximately 8-15% mature spores according to NEWA models. This will likely be our first significant infection period of the 2016 season, and growers should be prepared. Bud stages are all over the map right now depending on location, from earliest green tip in the colder uplands to late half-inch green tip / early tight cluster in the warmest valleys. Winds look a bit on the high side today but drop down to reasonable levels for spraying by late afternoon/this evening and through tomorrow, so this looks like the best window to apply protective materials.
Apple Scab infection period expected Monday night through Tuesday, April 25-26
Green tip in Vermont orchards and disease management
April 15, 2016
By later today most orchards in the Champlain and Connecticut valleys and Bennington area should be into green tip and disease management activities will need to commence soon for the 2016 season. The weather forecast for rain on Monday has been somewhat inconsistent with chances decreasing since last night, but growers should be ready for when any rains do come. That said, aside from the 30-40% chance called for on Monday, next week looks relatively dry. Depending on when we assume mature scab ascospores to be present in the orchard, we may have 2-6% ascospore maturity by Tuesday in most orchards. That may not seem like much, but many orchards had significant scab last year and 2% of a lot is still quite a spore load.
The threat of freezing weather is diminishing with forecast lows above freezing in the major fruit growing regions of the state after tonight. This means that both copper and oil should be okay to apply starting tomorrow through next week. I have seen and heard of increasing problems with San Jose scale in Vermont orchards, and a thorough oil application is the first line of defense against those insects as well as overwintering mites. Horticultural oil should be applied at 2% volume and in as much water as practical, certainly no less than 100 gallons per acre and more if you can on larger trees. This means slower travel and more refilling of the tank, so plan accordingly. Copper is the first line of defense against fire blight and while that disease was not present at high levels in Vermont orchards last year (in general…), it is out there and has become an increasing problem in the state in the past decade. A copper spray will also provide about seven days’ protection against apple scab and can be combined with oil. Fixed copper materials are best at this time, and specific materials and rates can be found in the 2015 New England Tree Fruit Management Guide. Care however must be taken with copper application, as the danger of phytotoxicity increases after green tip and especially by half-inch green tip. My suggestion is to get out there as soon as possible starting tomorrow and cover the whole orchard with a copper-oil mix before buds advance too far. When using oil, it is important to not use Captan for 7-10 days to avoid phytoxicity.
For orchards that have green tissue and were not covered with a fungicide, if an infection period occurs on Monday-Tuesday April 18-19, a kick-back fungicide may be called for to prevent infection because copper has no post-infection activity. The anilinopyrimidine (AP) fungicides Vangard and Scala have decent (48-72 hour) post-infection activity, work well in cooler weather, and are poor on fruit scab and are therefore good choices to use early in the season. Like all post-infection materials, there is potential for resistance development to the fungicide in local scab populations so a tank mix with a contact fungicide is recommended. I do not know of issues with copper and AP compatibility although there are no warnings on the label. If not using copper at this time, then mancozebs are another good material that will provide some protection against the disease (but have no kick-back activity of their own).
After this current round of treatment is completed, growers should begin their early season fungicide schedule going into the following week. Generally the mancozebs are the best candidates for maintaining protective coverage, although total use restriction must be followed (i.e. no more than four sprays through bloom at the six pound per acre rate of Manzate or equivalent or seven sprays up to the 77-day preharvest interval at the three pound per acre rate). After the seven-day ‘embargo’ following an oil application, Captan may also be used either alone or in combination with mancozeb (using a half-rate of each). If using Captan, recognize that there is a 40 pound per acre seasonal limit, so early season uses may limit its use later in the season for secondary scan and summer disease control.
Organic growers of course will be limited primarily to elemental fungicides including copper (apply that now, by the way) and sulfur materials. After the seven-day window that you buy with a copper spray, elemental sulfur applied at ten pounds per acre on a weekly basis or more often if more than one inch of rain falls is the primary line of defense against apple scab on susceptible cultivars. Growers do have the option of using liquid lime sulfur which has some post-infection activity but is very caustic, phytotoxic, and frankly nasty to apply, so good preventative coverage with elemental sulfur is important to manage the disease.
As always, apple scab and other pest management decisions should be made using best information on the conditions in your orchard. The apple scab primary ascospore infection season lasts roughly from green tip (judged by 50% of McIntosh buds having reached that stage) through 900 degree days base 32°F. Growers located near a NEWA station may use the models for the station closest to them, with the caveat that they may not be exact for their specific site. When using the scab model for a particular site, NEWA asks for a green tip date to be entered, and the default date is quite a bit ahead of what we are seeing in orchards. That said, entering an earlier date will allow you to be more conservative regarding ascospore development early in the season. For example, the default green tip date for Putney is March 30, which estimates 6% ascospore maturity by April 20, whereas entering a date of April 15 gives an estimated ascospore maturity of 2%. The only way to truly know the ascospore maturity level in orchards is to perform spore trapping or squash mounts using a microscope and very exacting and time-consuming technique, which is rarely done. The models are just that, computed estimates of biological activity in the orchard and only output what the model and entered conditions tell it to. That said, we know we are entering the scab season for this season, so growers should plan to apply coverage through the end of primary ascospore release. However, as we know that leaf wetness is required to initiate scab infection, extended dry periods will reduce the need for preventative coverage, but growers should be careful to not get caught entering a wet period without any coverage on trees.
New NEWA stations in Vermont! This spring we have brought one more NEWA station on-line in Bennington and have moved the Calais station from my house to a relatively new orchard in East Montpelier, which brings the total number of NEWA stations to ten, in addition to the airport sites located around the state. Remember that airport sites do not have leaf wetness sensors so apple scab and other disease models requiring that information cannot be run, but insect models will function fine.
Best wishes and good luck on the start of the season.
-TB
Pre-bud break grape management
April 15, 2016
In these next few days and week(s) before buds start swelling on grapes in Vermont, there are a few activities that can be performed that may improve management in your vineyard for the 2016 growing season. First of course is wrapping up any pruning, including careful removal of any disease inoculum including diseased wood and mummy berries that may harbor black rot and phomopsis. Now is also a good time to consider a dormant lime sulfur spray to further reduce disease inoculum. Mark Longstroth from Michigan State University Extension outlined the principles of dormant lime sulfur application in vineyards in an April 16, 2011 posting:
“Lime sulfur is an effective dormant spray when applied early in the season as growth begins. When applied as a true dormant spray before growth begins, lime sulfur can be used with oil to increase the penetration of the caustic sulfur into the surface of the infected tissues. Once green tissue appears, [lime sulfur] should not be mixed with oil. Oil will carry sulfur into green plant tissue causing injury. It is generally recommended to not use oil within a week of a sulfur spray when green tissue is exposed. Lime sulfur rates should be reduced when green tissue is exposed. Recommended rates vary for different products with dormant rates in the 10 to 12 pounds per 100 gals of water to 5 or 6 pounds when green tissue is exposed. Lime sulfur (calcium polysulfide) is a caustic material and after application it breaks down, releasing sulfur. It is very effective against diseases that overwinter on the host. Lime sulfur is also effective against many insect pests that overwinter on the plant.”
Remember that lime sulfur is pretty ‘hot’ stuff and requires that applicators follow precautions to reduce contact with the material. Very good coverage is required for this material to work, and the target zone of the trunks and cordons small, so application with a handgun may be best. If using an airblast sprayer, consider shutting off the fan to reduce drift, although that will require application on a relatively windless day. Airblast or boom sprays are also difficult to target the trunks without substantial overspray to the open space between trunks.
Now is also a good time to consider chemical weed control applications if you will be using that method. I outlined the best practices in applying early spring herbicides in an April 24, 2014 post: “…It is important to avoid herbicide contact with green tissue. Grapes are especially sensitive to many herbicides, so early spring before bud break is a good window for application of materials if you will be using them in the vineyard. Young vines with thin bark on the lower trunk can also be damaged by herbicide contact, so shielded sprayers or waxed trunk guards should be used.
Specific herbicide materials and their use restrictions and guidelines ca be found in Chapter 6 of the New York and Pennsylvania Pest Management Guidelines for Grapes
In February 2013, a Northern Grapes Project Webinar on vineyard groundcover management was offered that can be viewed here:
http://youtu.be/pSNy08aEs4E
Also, slides from vineyard weed identification and management presentations made to growers at the Northwest Michigan Horticultural Research Center from April 17, 2014 are available here:
http://bit.ly/1kdeGWp
The window to best manage weeds with herbicide applications is short, so please consider getting out there in the next couple of weeks. Once weeds get established in the vineyard and vines start growing, under trellis groundcover management becomes very difficult without causing vine injury.
-Terry
April 2016 Northern Grapes Project News You Can Use – Itasca Grape
News You Can Use
Itasca – New White Grape from the University of Minnesota
April 2016
Itasca grape.
Photo: David Hansen
The University of Minnesota recently released its fifth cold-hardy wine grape, named ‘Itasca.’ Itasca arose from a 2002 cross made by Peter Hemstad between Frontenac gris and MN 1243, and was identified in 2009 as an elite seedling.
Matthew Clark, assistant professor and grape breeder at the University of Minnesota, said “Itasca offers many benefits to wine grape growers over some of the currently available varieties. This is because it has much lower total acidity, disease resistance, phylloxera resistance, and can withstand cold temperatures. It appears to be even more cold-hardy than Frontenac. Itasca berries and wine are flavorful with notes of melon, pear, quince, and minerality.”
Data provided by Clark show that at harvest, titratable acidity in Itasca averages close to 10 g/L, while La Crescent is 14.5 g/L and Frontenac gris is 15.5 g/L. After the Polar Vortex winter of 2014, Itasca had over 60% primary bud survival, while other white cultivars had less (Frontenac gris, 20%: Frontenac blanc, 35%; La Crescent, 30%).
Licensed nurseries will begin selling Itasca in 2017.
Below are links to other articles and videos about Itasca.
University of Minnesota press release: http://discover.umn.edu/news/food-agriculture/university-minnesota-releases-its-latest-cold-hardy-wine-grape
CBS Minnesota: http://minnesota.cbslocal.com/2016/04/04/u-of-m-white-wine-grape/
Wines and Vines article: http://www.winesandvines.com/template.cfm?section=news&content=167366
The Northern Grapes Project is funded by the USDA’s Specialty Crops Research Initiative Program of the National Institute for Food and Agriculture, Project #2011-51181-30850
Chrislyn A. Particka, PhD
Extension Support Specialist
Cornell University
School of Integrative Plant Science, Horticulture Section
630 W. North Street
Geneva, NY 14456
cap297
Recent cold and potential damage, plus apple scab management.
11 April 2016
If it weren’t for that warm spell, everything would be all right. Orchards around Vermont are largely at the ‘advanced silver tip’ bud stage and have been since the first of April, with tighter buds on Honeycrisp and in cooler upland orchards and more advanced buds at green tip on early cultivars and in warmer areas. Recent cold temperatures, especially on April 5, when we saw 10°F in South Burlington, are cause for concern, but don’t write off the crop yet. Critical temperatures for bud damage to apples at silver tip are 15°F for 10% kill and 2°F for 90% kill as a rule of thumb, although many factors can adjust those numbers. If buds were more advanced to the green tip stage, then the 10% and 90% kill temperatures are 18 and 10°F, respectively. I have only looked at a handful of buds at the UVM orchards, and saw a few with browning in the flower primordia. I prefer to take a wait and see approach because I just don’t trust evaluations yet, I don’t feel the damage was too extensive, and we still need to manage our trees for disease in the early spring regardless of whether there is a crop or not.
Apple scab management is right around the corner, and when the warm temperatures arrive by the weekend we can expect rapid bud stage development and plenty of green tissue exposed that will need protection. Many orchards has issues with late-season apple scab in 2015 and inoculum may be on the high side, so it would make sense to keep things covered during early scab infections this year. Luckily, the cool/cold weather has kept ascospore maturity low, with NEWA estimating 2% maturity in South Burlington and a predicted 3% of spores mature by the weekend. However, warmer sites like Putney are predicting maturity of 5% by this weekend, and if inoculum is high, 2-5% can cause substantial infection. Rains are expected for next Tuesday, and while I wouldn’t put too much faith in an eight-day forecast, I would plan on protecting trees as soon as possible after green tip emerges. This likely means spraying Friday and through the weekend. Remember to avoid using phytotoxic materials (coppers, captan, oil) before or after a freeze. Copper would be preferred for its efficacy against fire blight at this stage as it’s probably the best and maybe only window to apply it before 1/2” green bud stage comes and chances for phytoxicity and fruit russeting increase. This may also be a good window for applying oil so long as you wait at least 24 and preferably 48 hours after a freeze event to avoid damaging developing tissues. As always, materials and rates are best found in the 2015 New England Tree Fruit Management Guide, please let me know if you need a copy.
Weather looks great for planting trees, so get them in the ground this week before you get pulled away with spraying later.
Early apple season considerations
As has been the case in the past several even-numbered years, growers are increasingly concerned about early bud break and potential for cold weather to damage developing apple buds. At the UVM Hort Farm, ‘McIntosh’ buds were just entering silver tip yesterday March 31. Growers are reporting silver tip across most of the major growing regions of the state, and a tiny bit of green tip has been mentioned. That may push out a bit today with warm temperatures, so some orchards may be in green tip by April 2.
This is a good time to look over and be familiar with the critical temperatures for bud damage in tree fruit. Michigan State University has published a guide at http://agbioresearch.msu.edu/uploads/396/36740/TreeFruitCriticalTemperatures.pdf
Based on this chart, orchards in silver tip can withstand 15°F with 10% fruit bud kill, and 2°F with 90% bud death. An orchard in green tip would have critical temperatures, respectively, of 18 and 10°F for 10% and 90% kill. It’s a pretty good bet that any bud development will slow through tomorrow, Saturday April 2 and halt after that through next week until warmer weather comes. So where you are at tomorrow is where your critical temperatures will be through the next expected cold spell. Orchard with no bud development (pre-silver tip) should be fine through this event.
Depending on where you are or what models you are looking at, low temperatures are expected to be in the teens on Monday and Tuesday mornings next week, and low spots will may be colder. There isn’t anything to do now but sit tight and see what comes. Get your pruning done and prepare your sprayers because the growing season will be here any time. I wouldn’t worry too much about early season scab right now unless significant green tip occurs, and even at that, it’s going to be tough to run sprayers around freezing weather (and definitively do not spray oil within 48 hours before or after a freeze event).
When the time comes, copper should be applied any time after green tip but before the half inch green ‘mouse ears’ stage. Copper’s primary benefit is in reducing overwintering populations of fire blight bacteria. Fire blight has become a regular disease to manage in Vermont, and a multi-pronged approach will be needed to keep it at bay. Copper applied at green tip will also give about seven days’ protection against apple scab. Applications should be made to all trees in the orchard, not just susceptible varieties. The specific copper material is less critical than the amount of metallic copper that is applied in the spray, and copper sulfate, copper hydroxide, copper oxychloride sulfate products all will be effective when used at label rates. I’ve attached a presentation by Kari Peter and Brian Lehman of the Plant Pathology Dept at Penn State that should provide good information on use of copper in early season apple sprays to manage fire blight inoculum and potentially that first scab infection period.
Now that the ground is clear and firming up, it also would be a good idea to perform spring orchard sanitation to reduce overwintering scab inoculum. Leaf shredding with a flail mower is an effective practice that also may be used to reduce small pruning wood to mulch, but the mower must be kept low in order to lift and grind leaves that harbor overwintering inoculum. Alternatively, there is still time to apply urea (40 lbs/100 gal water/acre) to leaf litter which aids in decomposition and breakdown of inoculum. Leaves should be wetted thoroughly and the majority of material directed into the tree row. This application would add 18 lb actual nitrogen per acre which should be accounted for in your fertilizer applications later in the season.
Important: UVM Cold-climate grape industry survey due April 15.
Tim:
Feel free to forward this to other NGP affiliates. Even though it refers to ‘Vermont and surrounding areas’, I am not against others filling it out so long as they enter their state so that I can sort the data.
Thanks, Terry
By: Terence Bradshaw
The University of Vermont Grape Program is conducting a survey of cold-climate grape producers to assess cultivar, training system, and yield patterns in Vermont and surrounding states’ vineyards. Producers from Vermont, other New England states, and northern New York are invited to participate. Results from the survey will inform important activities in support of grape and wine producers in the region. For example, we recently submitted a letter of intent to the Vermont Specialty Crops Block Grants Program to conduct research on issues relevant to our maturing industry, including evaluation of promising new cultivars and adaptation of pruning and training systems that address needs of mature vineyards. Another recently-funded project through the Northeast IPM Center submitted by Team member Dr. Ann Hazelrigg will develop a Pest Management Strategic Plan for cold-climate grapes. This thorough survey of vineyards in the region will provide important data that will guide these and other projects. In addition, data from the survey, including prices received by growers for cold-climate cultivars, may be used to develop realistic revenue estimates for use in crop insurance programs.
The survey may be found at: https://survey.uvm.edu/index.php/229889/lang-en.
It will not take long to take the survey, but it would be helpful to have records on planting date, cultivar, training system, and yield available when you complete it. The survey has been approved by the UVM Institutional Research Board and all data is collected anonymously and no information identifiable to specific vineyards will be collected or published in any resulting reports. The survey will be open until April 15.
Thank you for your participation and feel free to distribute the link to other growers in the region.
April 12th Northern Grapes Project Webinar Announcement and Registration
The Northern Grapes Project Webinar Series
“Northern Grapes Project Research Results: Fungicide Sensitivity and Vine Nutrition of Cold-Hardy Cultivars”
Tuesday, April 12th, 2016
12:00 Noon Eastern (11:00 am Central)
7:00 pm Eastern (6:00 pm Central)
Join Patricia McManus of the University of Wisconsin-Madison and Carl Rosen of the University of Minnesota as they discuss results of their Northern Grapes Project research. Patty’s presentation will summarize four years of field trials that focused on determining the sensitivity of popular cold-hardy cultivars to fungicides, including copper, sulfur, and difenoconazole. Carl’s presentation will summarize three years of research on tissue analysis of cold hardy grapes grown in 16 locations spanning five states. Nutrient diagnostic criteria will be presented for petiole, blade, and whole leaves collected at bloom and veraison and relationships between soil properties/tissue nutrient concentrations and grape juice quality will be discussed.
If you have received this email from someone other than Chrislyn Particka, you need to register via the link below:
https://cornell.qualtrics.com/jfe/form/SV_bsdhmqRd13JqYNT
Registering for one Northern Grapes Webinar will place you on the mailing list, and you will receive announcements and connection instruction for all further Northern Grapes Webinars.
Registration will close at 8 am (Eastern) on Friday, April 8th.
Registration is NOT required if you received this email directly from Chrislyn Particka, as it means that you are a member of the Northern Grapes Webinar mailing list.
All members of the Northern Grapes Webinar mailing list will receive an email the Friday before the webinar containing the web address (URL) for both webinar sessions as well as connection instructions.
There is no charge for this webinar. If you cannot attend one of the live sessions, recordings of all webinars are posted on our website (http://northerngrapesproject.org/?page_id=257) within one week of the webinar date.
Feel free to email Chrislyn Particka (cap297) with any questions, if you want to check your registration status, or if you’d like to be removed from the Northern Grapes Webinar mailing list.
Please note: WebEx will no longer be supporting the following operating systems:
• Windows Server 2003
• Windows XP
• Mac OS X 10.6
This means that WebEx users will be unable to join or start WebEx meetings, or use any other WebEx application from computers that use these operating systems. Please upgrade computers to a supported operating system so you can continue to use WebEx without interruption.
Further Northern Grapes Project information is available on-line at
The Northern Grapes Project is funded by the USDA’s Specialty Crops Research Initiative Program of the National Institute for Food and Agriculture, Project #2011-51181-30850.
Chrislyn A. Particka, PhD
Extension Support Specialist
Cornell University
School of Integrative Plant Science, Horticulture Section
630 W. North Street
Geneva, NY 14456
cap297
Primary bud winter injury low on grapes in UVM vineyard
As we all know, the winter of 2015-2016 in Vermont was largely a bust, with (virtually) no snow and generally warm temperatures. The no snow factor would have been concerning if we had extended periods of sub-zero temperatures, but with the exception of February 13-14 when we recorded temperatures of -13-14°F in South Burlington, that deep freeze didn’t come. Thankfully, the warm weather experienced in early March has subsided, and vines are not showing any sign of premature bud break. The extended weather looks to remain relatively cool, but a warmup is expected to begin next week. It’s time to wrap up pruning in Vermont vineyards in the next few weeks.
Growers should aim for a balanced vine during pruning, leaving 4-6 buds per foot of canopy. This would be adjusted up in cases of high primary bud mortality from winter cold damage, but damage observed at the UVM vineyard was generally below the 15% threshold where we consider leaving additional buds to compensate for those that were damaged. 2016 Primary Bud Mortality can be found at: http://www.uvm.edu/~fruit/grapes/uvmvineyard/2016UVMwinterbudinjury.pdf.
We encourage growers to collect their own primary bud mortality data prior to pruning, if possible. The procedure is fairly quick and requires no special equipment besides a hand lens or magnifying viewer. A helpful video from the Cornell Cooperative Extension Finger Lakes Grape Program that outlines the process may be found at: https://www.youtube.com/watch?v=_RHJ5mY3fAs .
Latest Tree Fruit management guide updates
By Terence Bradshaw
As mentioned at the 2016 VT Tree Fruit Growers Association meeting in February, there will be no reprint of the New England Tree Fruit Management Guide in 2016. 2015 guides are still available at: https://www.regonline.com/newenglandtreefruitmanagementguide.
The attached document contains any changes in chemical registrations that we know of to-date, and may be printed and kept as an addendum to the guide. Thanks go to Mary Conklin, Heather Faubert, Jon Clements, Glen Koehler, and the other authors of the guide for help in compiling the information.